Concept

Off-the-Record Messaging

Related publications (15)

On the Theory and Practice of Modern Secure Messaging

Billions of people now have conversations daily over the Internet. A large portion of this communication takes place via secure messaging protocols that offer "end-to-end encryption'" guarantees and resilience to compromise like the widely-used Double Ratc ...

EPFL2024

Cryptographic Administration for Secure Group Messaging

Serge Vaudenay, Daniel Patrick Collins

Many real-world group messaging systems delegate group administration to the application level, failing to provide formal guarantees related to group membership. Taking a cryptographic approach to group administration can prevent both implementation and pr ...

Berkeley2023

Groove: Flexible Metadata-Private Messaging

Ludovic Barman, David Lazar

Metadata-private messaging designs that scale to support millions of users are rigid: they limit users to a single device that is online all the time and transmits on short regular intervals, and require users to choose precisely when each of their buddies ...

Usenix Assoc2022

Analysis and Improvements of the Sender Keys Protocol for Group Messaging

Daniel Patrick Collins

Messaging between two parties and in the group setting has enjoyed widespread attention both in practice, and, more recently, from the cryptographic community. One of the main challenges in the area is constructing secure (end-to- end encrypted) and effici ...

2022

Determining the Core Primitive for Optimally Secure Ratcheting

Serge Vaudenay, Muhammed Fatih Balli

After ratcheting attracted attention mostly due to practical real-world protocols, recently a line of work studied ratcheting as a primitive from a theoretic point of view. Literature in this line, pursuing the strongest security of ratcheting one can hope ...

2020

Symmetric Asynchronous Ratcheted Communication with Associated Data

Serge Vaudenay, Hailun Yan

Following up mass surveillance and privacy issues, modern secure communication protocols now seek strong security, such as forward secrecy and post-compromise security, in the face of state exposures. To address this problem, ratcheting was thereby introdu ...

Springer, Cham2020

Time in cryptography

Gwangbae Choi

Time travel has always been a fascinating topic in literature and physics. In cryptography, one may wonder how to keep data confidential for some time. In this dissertation, we will study how to make private information travel to the future. This dissertat ...

EPFL2020

Bidirectional Asynchronous Ratcheted Key Agreement with Linear Complexity

Serge Vaudenay, Fatma Betül Durak

Following up mass surveillance and privacy issues, modern secure communication protocols now seek more security such as forward secrecy and post-compromise security. They cannot rely on an assumption such as synchronization, predictable sender/receiver rol ...

Springer2019

Reducing Metadata Leakage from Encrypted Files and Communication with PURBs

Jean-Pierre Hubaux, Bryan Alexander Ford, Ludovic Barman, Kirill Nikitin, Wouter Lueks, Matthew Joshua Underwood

Most encrypted data formats leak metadata via their plaintext headers, such as format version, encryption schemes used, number of recipients who can decrypt the data, and even the recipients’ identities. This leakage can pose security and privacy risks to ...

Sciendo2019

Generating Steganographic Text with LSTMs

Martin Jaggi, Aikaterini Argyraki, Tina Fang

Motivated by concerns for user privacy, we design a steganographic system ("stegosystem") that enables two users to exchange encrypted messages without an adversary detecting that such an exchange is taking place. We propose a new linguistic stegosystem ba ...

2017

Atom: Horizontally Scaling Strong Anonymity

Bryan Alexander Ford, Henry Nathaniel Corrigan-Gibbs

Atom is an anonymous messaging system that protects against traffic-analysis attacks. Unlike many prior systems, each Atom server touches only a small fraction of the total messages routed through the network. As a result, the system’s capacity scales near ...

Association for Computing Machinery2017

Matryoshka: Hiding Secret Communication in Plain Sight

Aikaterini Argyraki, Christina Fragouli, Iris Safaka

We want to enable a pair of communicating users to exchange secret messages while hiding the fact that secret communication is taking place. We propose a linguistic steganography approach, where each human message is hidden in another human-like message. A ...

2016

Building Security Protocols Against Powerful Adversaries

Iris Safaka

As our sensitive data is increasingly carried over the Internet and stored remotely, security in communications becomes a fundamental requirement. Yet, today's security practices are designed around assumptions the validity of which is being challenged. In ...

EPFL2016

Secret message capacity of erasure broadcast channels with feedback

Christina Fragouli, Suhas Diggavi, László Czap, Vinod Malathidevi Prabhakaran

We characterize the secret message capacity of a wiretapped erasure channel where causal channel state informa- tion of the honest nodes is publicly available. In doing so, we establish an intimate connection between message secrecy and secret key generati ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

User-Aided Data Authentication

Sylvain Pasini

All classical authentication protocols are based on pre-shared authentic information such as long-term secret keys or a public key infrastructure. However, there are many practical settings, where participants can additionally employ authentic Out-Of-Band ...

2009